Cell division and differentiation are tightly regulated during normal development. Plant meristems are groups of stem cells that divide to generate more meristem cells, and differentiated cells that make up all the structures of the mature plant. Floral meristems are determinate in that they generate a limited number of organ primordia and ultimately are consumed by organogenesis. Therefore, floral meristems must carefully balance cell division and differentiation. This broad objective of this proposal is to understand the molecular regulation of floral development in the model system, maize. Specifically, I will focus on two genes required for organ specification and determinacy in the floral meristem, bearded-ear (bde) and fuzzy tassel (fzt). The molecular nature of fzt is unknown, and I will identify the fzt gene by positional cloning, bde encodes a member of the MADS-box protein superfamily. MADS-box proteins have diverse roles in both plants and animals and other MADS-box proteins also regulate cell division and differentiation. MADS-box proteins cooperate with other proteins to regulate the gene expression and I will identify BDE-interacting proteins using the yeast two-hybrid system. In addition, I will identify BDE-target genes using expression profiling. Finally, I will integrate bde and fzt into the floral regulatory network using double mutant analysis and RNA expression studies. The proposed experiments will increase our understanding of maize floral development, and the fundamental biological problems of pattern formation and cell fate specification. The proposed experiments tackle fundamental biological problems common in both plants and animals, including pattern formation and cell fate specification. Understanding the molecular regulation of normal development is critical to understand what goes wrong in genetic diseases such as cancer. I will investigate how two genes, bearded-ear and fuzzy tassel, regulate cell division and cell fate specification during floral development in the model system, maize. While there are likely to be differences between plants and animals in how these processes are regulated, findings in plants might also provide novel insights into animal development